Move presence state out of the server

[mikklfr]

Today the presence messages are managed exclusively by the node process running sugarizer.

In order to get the ability to have multiple workers working at the same time or to be able to recover a process crash without loosing state, it would be great to work on the High Availability (HA) of Presence.

My first research would made us look at Redis Pub/Sub.
Redis can be used in HA or as a managed service.